1. Field of the Invention
The present invention generally relates to a hybrid electrical and fiber optic connector for a submarine streamer, and, more particularly, to a connector with contacts secured to insulation by a resiliently biased part latching behind a shoulder or into a recess.
2. Description of Related Art
Reflection seismology is one of the most important tools available to petroleum geophysicists for surveying subsurface geologic formations in connection with petroleum exploration. During a typical seismic prospecting survey, energy in the form of an impulse, explosion, or continuous vibration is introduced into the ground near the surface of the earth. The energy waves spread in all directions from the source and are partially reflected by underground structural discontinuities, such as the interfaces between different types of rock. Sensors, called geophones, detect these reflected waves as small displacements of the earth's surface which are then converted into electrical signals that can be recorded, processed, and further analyzed. For example, the time required for the reflected energy to return to the surface at a particular location can be used to determine the depth of the rock interfaces at that location. By plotting this return time for an array of such geophones at various locations along the surface, geophysicists can then assemble a picture of the subsurface rock layers at various depths.
For marine seismic prospecting, hydrophones are used to record the excess pressure generated by reflected sound waves in the water along a profile line being surveyed. The hydrophones are part of a cable, called a submarine streamer, that typically includes a strength member surrounded by numerous electrical conductors or optical fibers for transmitting signals from the hydrophones to a recording device on a tow ship. A single ship moving at 4-6 knots might pull a 10,000 foot long streamer cable having twenty-four or more sections, or stations, joined by connectors. Each streamer station will include ten to forty hydrophones for sensing the reflected energy waves from an explosive gas source, or continuous bubble source, near the ship which is activated over roughly ten to thirty-second intervals. In this manner, a typical seismic survey ship can thus survey about 50 miles of line each day.
Each section of the streamer may include forty, or more, signal transmission lines terminating at male and female connectors on the ends of that section of the streamer. In order to provide accurate information, each of the sections is preferably towed at constant depth, typically thirty-five to forty feet below the surface of the water. However, the streamer can also be exposed to much greater depths. The streamer sections are therefore enclosed in a flexible, plastic sheath which not only provides protection against abrasion and corrosion due to infiltration of salt water, but also allows the streamer to be buoyancy balanced along its length. This balancing is typically accomplished by filling the sheath with a liquid that floats on water (usually a buoyant, kerosene-like liquid such as noroma) and/or by adding lead tape to the exterior of the sheath to provide the appropriate buoyancy at each point along the streamer.
A serious problem arises when the terminating pins, or contacts, disposed in the connectors at either end of a section of the streamer are short-circuited by a conductive buoyancy balancing fluid leaking from the sheath. The contacts may also be exposed to corrosive salt water from the leaking sheath if it is punctured or otherwise damaged. This problem has been addressed in the past by applying a suitable potting compound to the backside of the connector. However, the potting compound is often ineffective at preventing the ingress of salt water and interferes with the repair and/or replacement of the contacts in the coupler.
U.S. Pat. No. 5,510,577 to Corrigan, incorporated by reference into the present application, discloses a multiple wire connector assembly for a marine streamer which addresses these problems by providing a sealing disk disposed between a connector insert and a compression disk. The compression disk is spring-loaded so as to force the sealing disk against the connector insert which then compresses conical nipples in the sealing disk against each of the individual conductor wires. However, leakage can still occur since the wires may bend near their entrance to the sealing disk. Furthermore, since all of the contacts in the connector are electrical contacts, a different connector must be used when fiber optic contacts, or other types of terminals, are required.